1. Field of the Invention
The present invention relates to a detergent composition, and, more particularly, to a neutral liquid detergent composition exhibiting remarkably reduced irritation and damage to the hair or the skin, possessing high foaming ability, and imparting a favorable feeling upon use. The detergent composition has also good rinsability of foam and excellent drainability from tableware and the like after washing.
2. Description of the Background Art
Because of increased awareness for safety towards the human body in recent years, a number of trials have been undertaken in order to moderate the action of detergent compositions which frequently contact the skin. Such detergent compositions include laundry detergents, dishwashing detergents, household detergents, hair shampoos, and body shampoos. One of the approaches is adjusting the pH of detergent compositions to a weakly acidic range, e.g. pH 5-6, close to the intrinsic pH of human skins so as to be mild to the skin. Another approach is to incorporate low irritant components as major detergent base components. For example, amino acid surfactants, alkyl phosphate surfactants, or the like are being used as a low irritant detergent (Japanese Patent Publication Nos. 40125/1975, 426023/1976, 9033/1980, and 27319/1983).
Even though these surfactants are low irritant, they do not necessarily exhibit sufficient detergency and foaming ability is also their drawback. On the other hand, sodium alkylbenzenesulfonates have conventionally been popular detergent base components for dishwashing detergents because of their strong detergency. The compounds, however, give a strong defattying action to the skin and thus can be a cause of roughened hands.
Because of these reasons, sodium alkylethoxysulfates which are less irritant to the skin have gained a wider popularity as the base components for dishwashing detergents in recent years. Their detergent performances are even promoted by incorporating co-surfactants such as tertiary alkyl amine oxides, higher fatty acid diethanolamides, and the like. Their mildness to the skin is also improved by such a combination as compared with conventional detergent compositions.
The mildness to the skin of the detergents has improved to some degree as described above, nevertheless the achievement at present is still unsatisfactory.
Alkyl glycosides, being saccharide-derived surface active agents, are less irritant compounds. Although they are nonionic surfactants, it is well known that they not only produce stable foam themselves but also can act as a foam stabilizer for anionic surfactants. Thus, alkyl glycosides are gaining much attention in recent years. Japanese Patent Laid-open No. 104625/1983, for example, discloses a foaming surfactant composition comprising an alkyl glycoside and an anionic surface active agent, and Japanese Patent Laid-open No. 74999/1987 discloses a liquid dishwashing detergent composition comprising an alkyl glycoside, an anionic surface active agent, and a fatty acid alkanolamide. They claim that the compositions are low irritant and have an excellent detergency. Even though these detergent compositions exhibit performances better than conventional detergent compositions containing polyoxyethylenealkylethers as a base component, such performances are still to be improved. They have problems such as an inferior feeling upon use, poor rinsability of the foam, and insufficient drainability.
In view of this situation, the present inventors have conducted extensive studies to make the maximum use of the characteristics of alkyl glycosides, and found that a detergent composition which exhibits an excellent feeling upon use, good rinsability of the foam, and superior drainability by incorporating alkyl glycosides together with a specific amount of certain type of nonionic surfactant having a specific HLB other than alkyl glycosides and a specific amount of certain type of water-soluble salt. Such findings have led to the completion of this invention.